Add YUV element convenience function.

Change-Id: Ie67dfba6a4c4f1913875ad9817c53e45d56809ae
diff --git a/graphics/java/android/renderscript/RenderScript.java b/graphics/java/android/renderscript/RenderScript.java
index 854f079..7d4a5c4 100644
--- a/graphics/java/android/renderscript/RenderScript.java
+++ b/graphics/java/android/renderscript/RenderScript.java
@@ -898,6 +898,8 @@
     Element mElement_LONG_3;
     Element mElement_LONG_4;
 
+    Element mElement_YUV;
+
     Element mElement_MATRIX_4X4;
     Element mElement_MATRIX_3X3;
     Element mElement_MATRIX_2X2;